soc: ti: ti_sci_pm_domains: Check for null return of devm_kcalloc

The allocation funciton devm_kcalloc may fail and return a null pointer,
which would cause a null-pointer dereference later.
It might be better to check it and directly return -ENOMEM just like the
usage of devm_kcalloc in previous code.

Signed-off-by: QintaoShen <unSimple1993@163.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/1648107843-29077-1-git-send-email-unSimple1993@163.com